JPS5930167B2 - Manufacturing method of fluorine-containing elastomer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a fluorine-containing elastomer, and more specifically, to a method for producing a novel fluorine-containing elastomer comprising a vinylidene fluoride-propylene-tetrafluoroethylene-fluorovinylether copolymer. It is something.

It has been known that propylene-tetrafluoroethylene copolymers can be made into excellent fluororubbers.

For example, Japanese Patent Publication No. 43-24199, U.S. Patent No. 3
See specification No. 467,635, British Patent No. 1,284,247, etc. However, such a fluorine-containing elastomer made of a propylene-tetrafluoroethylene copolymer is
Although it has excellent heat resistance, chemical resistance, etc., it has insufficient solvent resistance, especially chlorine solvent resistance, and low-temperature properties.
Based on the recognition of the above-mentioned problems, the present inventor has conducted various studies and examinations in order to provide a means for improving the solvent resistance and low-temperature properties of propylene-tetrafluoroethylene copolymers. As a result, it has been found that the object can be advantageously achieved by copolymerizing a fluorovinyl ether, such as perfluoropropyl vinyl ether, with vinylidene fluoride and ethylene tetrafluoride and propylene.

That is, by copolymerizing fluorovinyl ether, especially perfluorovinyl ether, with vinylidene fluoride, benzene, carbon tetrachloride, trichloroethylene can be produced without impairing the heat resistance, chemical resistance, etc. of the propylene tetrafluoroethylene copolymer. It has been newly discovered that the durability against organic solvents such as , acetone, and methyl chloroform can be improved beyond a practical level, and the low-temperature properties can also be improved. Thus, the present invention has been completed based on the above discovery, and consists of copolymerizing vinylidene fluoride, propylene, ethylene tetrafluoride, and fluorovinyl ether by the action of a polymerization initiator to obtain a total of 30 to 70 moles. % vinylidene fluoride, 3~
A method for producing a fluorine-containing elastomer, which comprises producing a copolymer elastomer containing 30 mol% propylene, 15 to 45 mol% tetrafluoroethylene, and 2 to 20 mol% fluorovinyl ether as constituent units. ,
This is a new offering.

The novel vinylidene fluoride-propylene tetrafluoride-fluorovinylether copolymer according to the present invention has a glass transition temperature of -10°C or lower and a thermal decomposition onset temperature of 350°C or higher, and can be prepared by suitable blending and processing. Sulfur produces a fluorine-containing elastomer with excellent heat resistance that exhibits high resistance to oil, acid, and alkali, as well as to organic solvents such as hydrocarbons, halogenated hydrocarbons, ketones, and esters. You can.

Furthermore, the fluorine-containing elastomer of the present invention has the problems of increased raw rubber hardness and decreased vulcanized rubber elasticity due to increased vinylidene fluoride content, which are observed in conventional tetrafluoroethylene-propylene-vinylidene fluoride elastomers. It is characterized in that this is effectively eliminated by the introduction of fluorovinyl ether units, and as a result, it has excellent roll workability and moldability, as well as excellent heat resistance, inorganic chemical resistance, and other properties. Furthermore, by introducing flexible vinylidene fluoride units, the cold resistance is improved compared to the tetrafluoroethylene-propylene elastomer.
Therefore, the packing material required to have such performance, o-
The fluorine-containing rubber can be advantageously applied to rings, diaphragms, gaskets, hoses, rolls, etc. According to the present invention, a new vulcanizable fluorine-containing elastomer comprising 15 to 45 mol% of ethylene tetrafluoride, 3 to 30 mol% of propylene, 2 to 20 mol% of fluorovinyl ether, and 30 to 70 mol% of vinylidene fluoride is obtained. In the present invention, 20 to 40 mol% of tetrafluoroethylene, 10 to 25 mol% of propylene, 5 to 1 mol% of fluorovinyl ether,
Particularly good results are obtained when the fluorine-containing elastomer contains 5 mol % of vinylidene fluoride and 35 to 65 mol % of vinylidene fluoride. If the content of fluorovinyl ether is too small, the effect of preventing the increase in hardness due to vinylidene fluoride described above will be lost, and the effect of improving solvent resistance will be insufficient; In this case, heat aging resistance is impaired and raw material cost increases, which is not preferable. If the content of vinylidene fluoride is too small, the effect of improving solvent resistance and cold resistance will be insufficient, and if the content is too large, the effect of improving resistance to inorganic chemicals and highly polar solvents will be insufficient. As the resistance decreases, the hardness increases, resulting in a decrease in workability and elasticity, which tends to impair the properties of an elastomer. Furthermore, compared to ethylene tetrafluoride, vinylidene fluoride is an expensive monomer and is disadvantageous in terms of cost. If the content of propylene is too low, the properties as an elastomer will be lost, and if the content is too high, it will be undesirable in terms of heat resistance, solvent resistance, chemical resistance, etc. Regarding the content of tetrafluoroethylene, it is desirable to select the above-mentioned range from the viewpoint of heat resistance, chemical resistance, moldability, flexibility of the polymer required as an elastomer, ease of acquisition, etc. In the present invention, examples of the fluorovinyl ether include conventionally known or well-known ones without particular limitation, but
Usually, perfluorovinyl ether is preferably employed.

For example, the general formula CF2=σ-0-[CF2CFXO].

-Rf (wherein Rf is a perfluoroalkyl group having 1 to 12 carbon atoms, X is a fluorine atom or a trifluoromethyl group, and n is an integer of O to 6). It is. Specifically, CF2
-CFOCF3, CF2=CFOC2F5, CF2-C
FOC3F7, CF2-CFOC5Fll, CF2-C
FOC8Fl7, CF2-CFOCF2CF2=CFO
CF2CF (CF3)0C3F7, CF2-CFOCC
Examples include F2CF(CF3)O]2C3F7.

In the general formula, Rf preferably has 1 to 5 carbon atoms, n preferably has O to 3 carbon atoms, and X preferably has a trifluoromethyl group in terms of ease of availability. . In addition, CF2-CFO (CF2)
1~7CF2H1CF2=CFO(CF2)1~7CF
2C1,. CF2-CFOCH2 (CF2) 0~6CF
3, CF2-CFO(CH2)0-7CH3, CH2=
CHOCH2 (CF2).

~6CF3, CH2-CHOCH2CH2 (CF2).
Of course, non-perfluorinated fluorovinyl ethers such as ~6CF3, CH2-CHOCF(CF3)2, and other fluorovinyl ethers having appropriate substituents may also be employed in the present invention. The copolymerization reaction in the present invention is
It can be carried out by various polymerization methods such as bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization, or by appropriate means such as catalytic polymerization using a polymerization initiator, ionizing radiation polymerization, redox polymerization, and the like.

In addition to the main components of vinylidene fluoride, ethylene tetrafluoride, propylene, and fluorovinyl ether, components copolymerizable with these, such as ethylene, isobutylene, acrylic acid and its alkyl esters, methacrylic acid and its alkyl esters, Vinyl chloride, propylene hexafluoride, chloroethyl vinyl ether, chlorotrifluoroethylene, etc. may be appropriately copolymerized. For example, 5
Copolymerization can be carried out in a small amount of about mol% or less. As for the molecular weight of the fluorine-containing elastomer, the intrinsic viscosity measured at 30°C in tetrahydrofuran is usually 0.01 to 1.
A value of 3 is desirable, especially 0.05 to 1.5.
A number average molecular weight in the range of 0.5 to 250,000 gives preferable results. The method of the present invention can be carried out using various polymerization methods or under various polymerization conditions as described above.

For example, it is carried out in organic solvents such as fluorinated or fluorinated chlorinated saturated hydrocarbons such as trichloromonofluoromethane, trichlorotrifluoroethane, and perfluorocyclobutane, so-called chlorofluorocarbon solvents, and alcohol solvents such as tertiary butanol. possible, in this case -40
A relatively low reaction pressure, for example a pressure of about 1 to 50 kg/Cd, can be employed at a temperature of about .degree. C. to +150.degree. Further, suspension polymerization or emulsion polymerization may be carried out using an aqueous medium, and in emulsion polymerization, polyfluorinated or polyfluorinated chlorinated alkyl-based dispersants can be preferably employed. Therefore, in such suspension polymerization and emulsion polymerization, chlorinated hydrocarbons, liquid hydrocarbons, dispersion stabilizers such as trichlorotrifluoroethane, tertiary butanol, reaction accelerators, etc. can be used as appropriate. . Also, acetone,
Molecular weight can be arbitrarily controlled using known chain transfer agents such as isopropyl alcohol, ethyl acetate, diethyl malonate, tetrahydrofuran, and acetaldehyde. Furthermore, it is possible to employ polymerization initiators such as peroxides, azo compounds, and persulfates, and the copolymerization reaction may also be carried out by irradiation with ionizing radiation such as gamma rays from cobalt-60. . In the case of polymerization in an aqueous medium, for example, 5 to 200 k9 at a temperature of about 50 to 100 °C.
/Cr! It can be carried out with a pressure of about i. Furthermore, it is also possible to use a low temperature of about 20° C. to +50° C. by using a redox initiator or the like. The method of the present invention can be carried out in any suitable manner, such as batchwise, semi-continuously, or continuously, and various polymerization conditions, polymerization operations, and polymerization methods may be used depending on the purpose or the polymerization method employed. It is desirable to select equipment, etc. In the present invention, after the various polymerization reactions,
The produced fluorine-containing elastomer can be separated by appropriate means.

For example, in a suitable emulsion polymerization method, the copolymer latex may be separated by a coagulation method in which an electrolyte is added to the copolymer latex after the polymerization reaction is completed, or a method in which the copolymer elastomer is separated by centrifugation after freezing, or by a method in which the copolymer elastomer is dried after being frozen. can. In the manner described above, a transparent to white fluorine-containing elastomer having rubber-like elasticity is obtained, and it is possible to advantageously produce a fluorine-containing elastomer that has better resistance to dissolution chiropractic than conventional propylene-tetrafluoroethylene copolymer elastomers. is possible.

The fluorine-containing elastomer thus obtained can be chemically crosslinked into a rubber-like crosslinked product using various crosslinking means, such as an organic peroxide, a polyvalent amine compound, or a nucleophilic reagent such as hydroquinone. It is also possible to carry out radiation crosslinking by irradiation with ionizing radiation such as γ-rays, γ-rays, and electron beams. In this case, various crosslinking aids, fillers, reinforcing agents, etc. can be added and mixed, and various vulcanization formulations can be adopted. The fluorine-containing elastomer obtained by the method of the present invention can be crosslinked by irradiation with ionizing radiation such as α rays, β rays, γ rays, neutron beams, accelerated particle beams, X-rays, and electron beams.

Usually, gamma rays from cobalt-60, accelerated particle beams, electron beams, etc. are preferred. For example, at a dose rate of 102 to 10 X roentgens/hour, especially 103 to 5X107 roentgens/hour, the irradiation dose is 104 to 108 rats, especially 10
It can be converted into a crosslinked copolymer by irradiating it with ionizing radiation to a range of about 3 to 5 x 107 rats. Therefore, ionizing radiation can be irradiated in air, and the irradiation atmosphere must be kept in a vacuum or under an air flow such as argon, helium, nitrogen, etc.
It can even be kept underwater. The crosslinking reaction caused by ionizing radiation irradiation proceeds efficiently even at or around room temperature, so there is no need to limit the irradiation temperature; it is also possible to adopt an irradiation temperature below room temperature, about 100°C, or higher. be. In addition, for crosslinking by ionizing radiation irradiation, the raw material copolymer is prepared in advance into a film, sheet, etc.
It has the advantage that it can be applied to objects formed into arbitrary shapes such as pipes, rods, rings, coatings, etc. Furthermore, the fluorine-containing elastomer obtained by the method of the present invention is
Crosslinking can be achieved by heating using a chemical crosslinking agent such as a peroxy compound.

For example, kyumene hydroperoxide, diisopropylbenzene hydroperoxide, di(tertiary butyl) peroxide, tertiary butyl cumyl peroxide, dicumyl peroxide, tertiary butyl peroxyacetate, tertiary butyl Organic monoperoxy compounds such as peroxybenzoate and 2,5-dimethyl-2
・5-di(tert-butylperoxy)-hexyne-3,
2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane, α-d-bis(tert-butylperoxy)-para-diisopropylbenzene, 2,5-dimethyl-2,5 Organic diperoxy compounds such as -di(benzoylperoxy)-hexane are preferred. Therefore, 5
A peroxy compound whose temperature gives a half-life of 100 to 200°C, preferably about 130 to 190°C,
It can be employed particularly advantageously as a chemical crosslinking agent. The amount of the chemical crosslinking agent used is not particularly limited and can be selected as appropriate, but it is usually about 0.1 to 20 parts by weight, preferably about 1 to 10 parts by weight, based on 100 parts by weight of the fluorine-containing elastomer. be. In crosslinking using amines, various alkyl amines such as hexamethylene diamine, tetraethylene pentamine, and triethylene tetramine, various aromatic amines such as aniline, pyridine, and diaminobenzene, and carbamic acid and cinnamylidene acid of these amines are used. Salts of fatty acids and the like can be used.

In addition, reagents with nucleophilic properties such as hydroquinone, bisphenol A, and catechol, and their alkali metal salts,
It is also possible to use an ammonium salt or the like in combination with a linear polyether or cyclic polyether such as polyethylene glycol or polypropylene glycol as an auxiliary agent. When crosslinking such a fluorine-containing elastomer, a conventionally known or well-known crosslinking aid may be used in both the method using ionizing radiation irradiation and the method using a chemical crosslinking agent.

For example, crosslinking aids such as allyl compounds, sulfur, organic amines, maleides, methacrylates, and divinyl compounds may be employed. Preferably, organic allyl compounds such as diallyl phthalate, triallyl phosphoric acid, triallyl cyanurate, triallyl isocyanurate, diallylmelamine, and para-benzoquinone dioxime, P-P'-
Oxime compounds such as dibenzoylbenzoquinone dioxime are used, and organic allyl compounds are particularly preferred. The amount of the crosslinking aid added is 100% of the fluorine-containing elastomer.
0.1 to 20 parts by weight, preferably 0.1 to 20 parts by weight.
About 2 to 10 parts by weight may be employed. Furthermore, various additives commonly used in conventional crosslinking methods may also be added during crosslinking of the fluorine-containing elastomer.

These additives may include metal oxides such as magnesium oxide, lead oxide, reinforcing agents such as carbon black, fine silica, and other fillers. pigments, antioxidants, stabilizers, etc. Therefore, when adding the various types of additives described above to the fluorine-containing elastomer, chemical crosslinking agents,
It is desirable to mix the crosslinking aid and other additives with the raw material fluorine-containing elastomer sufficiently and uniformly.

Such mixing may be carried out using conventional rubber kneading rolls, Banbury mixers, or the like. Working conditions during mixing are not particularly limited, but usually 30
By kneading at a temperature of about 80 DEG C. for about 10 to 60 minutes, the additive compound can be sufficiently dispersed and mixed into the fluorine-containing elastomer. The working conditions and operations during mixing are preferably carried out by selecting optimal conditions depending on the type and purpose of the raw materials and ingredients used. The operation of thermal crosslinking using a chemical crosslinking agent is as follows:
Conventionally conventional operations can be employed.

For example, an operation of heating while pressurizing in a mold may be employed, or an operation of heating in a heating furnace after molding by extrusion or injection molding may be employed. It is desirable to select optimal conditions for the working conditions during thermal crosslinking depending on the raw materials and formulation used. The temperature during thermal crosslinking may be generally about 80 to 250°C, preferably about 150 to 200°C. Further, the heating time is not particularly limited, but is selected in the range of 1 minute to 3 hours, preferably in the range of 5 minutes to 1 hour, depending on the chemical crosslinking agent and the purpose of molding. The heating time can be shortened by increasing the heating temperature. still,
It is also possible to reheat the resulting crosslinked copolymer,
It is useful for improving physical properties. For example, 150
1 at a temperature of ~200°C, preferably 180-230°C.
Reheating treatment for about 5 to 25 hours may be employed. The crosslinked fluorine-containing elastomer obtained by the present invention has excellent heat resistance, chemical resistance, etc., as well as solvent resistance and cold resistance, so it can be used in various applications that require rubber elasticity under a wide range of usage conditions. can be used to advantage.

For example, oil-resistant, chemical-resistant, heat-resistant packing, O-rings and other sealing materials, diaphragms, valves in transportation vehicles such as automobiles, ships, and aircraft, and similar packings, O-rings, sealing materials, diaphragm valves, and hoses in chemical plants. , rolls, tubes, acid-resistant coatings, linings, etc. In addition, as mentioned above, it has excellent processability, so it can be formed into pipe-shaped, rod-shaped products, etc., and it can also be processed into film-shaped or tape-shaped products, which can then be laminated, pasted, or wrapped. Of course, it is also possible to perform further molding processing by secondary processing such as. Next, examples of the present invention will be described in more detail, but it goes without saying that the present invention is not limited by this description. Examples 1 to 3 and Comparative Examples 1 to 2 Deoxygenated water, ammonium persulfate (APS), sodium bisulfite (SBS), disodium phosphate, and 12
Charge water salt (DSP) and ammonium perfluorooctanoate (FC-143).

After purging the autoclave with nitrogen, vinylidene fluoride, tetrafluoroethylene, and propylene were introduced in the amounts shown in Table 1. Next, stirring was started at 300 rpm and the reaction was continued under the polymerization conditions shown in Table 1. During the reaction, monomers were replenished according to the composition shown in Table 1 so as to keep the pressure constant. After the reaction was completed, the monomer was purged, the latex was extracted, and after coagulation with a 1% CaCl2 aqueous solution, it was washed and dried to obtain a copolymer with the same polymerization results shown in Table 1. The composition of the resulting copolymer is also shown in Table 1.
These copolymers were vulcanized according to the formulations and vulcanization conditions shown in Table 2 below, and the main mechanical properties and solvent resistance test results of the resulting vulcanizates are also summarized in Table 2.

In addition, tetrafluoroethylene-propylene copolymer (C2F4
/C3H6 molar ratio 55/45) and vinylidene fluoride-tetrafluoroethylene propylene copolymer (C2H2F2/
C2F4/C3H6 molar ratio 55/30/15) was also vulcanized in the same manner as in Examples 1 to 3, and the test results of the resulting vulcanizates are shown in Table 2 as Comparative Examples 1 and 2, respectively. In addition, the solvent resistance test of the vulcanizate in Table 2 below *(
was carried out as follows.

That is, from a vulcanized sheet (thickness 2 mm) to 2 (1-J mo V!
A corner test piece was cut out, and the volume swelling ratio by solvent immersion was measured in accordance with JIS, K63Ol. Examples 4 to 5 The composition, molecular weight, and peroxide addition of the copolymer obtained by conducting polymerization under exactly the same conditions as in Examples 1 and 2 except that CF2-CFOCF2CF(CF3)0C3F7 was used instead of CF2-CFOC3F7. The physical properties of the vulcanized product were measured using sulfur.

Claims (1)

[Claims] 1. Vinylidene fluoride, propylene, tetrafluoroethylene, and fluorovinyl ether are copolymerized by the action of a polymerization initiator to form 30 to 70 mol% vinylidene fluoride and 3 to 30 mol% propylene. , 15 to 45 mol % of ethylene tetrafluoride, and 2 to 20 mol % of fluorovinyl ether as structural units. 2. The method for producing a fluorine-containing elastomer according to claim 1, wherein perfluorovinyl ether is used as the fluorovinyl ether. 3 General formula CF_2=C as fluorovinyl ether
F-O-[CF_2CFXO]_n-Rf (wherein, Rf is a perfluoroalkyl group having 1 to 12 carbon atoms,
X is a fluorine atom or a trifluoromethyl group, n is 0 to 6
A method for producing a fluorine-containing elastomer according to claim 1 or 2, using perfluorovinyl ether represented by (respectively an integer of). 4. The method for producing a fluorine-containing elastomer according to claim 1, wherein the copolymerization is carried out in an aqueous medium containing a polyfluorinated or polyfluorinated chlorinated alkyl dispersant. 5 Temperature of 50-100℃ and 5-200kg/cm^
5. The method for producing a fluorine-containing elastomer according to claim 4, wherein the copolymerization is carried out at a pressure of 2. 6 Vinylidene fluoride 35-65 mol%, propylene 1
0 to 25 mol%, tetrafluoroethylene 20 to 40 mol%,
A method for producing a fluorine-containing elastomer according to claim 1, which produces a copolymer elastomer containing 5 to 15 mol% of fluorovinyl ether. 7 Temperature of -40 to +150 °C in organic solvent and 1 to 5
The method for producing a fluorine-containing elastomer according to claim 1, wherein the copolymerization is carried out at a pressure of 0 kg/cm^2. 8. The method for producing a fluorine-containing elastomer according to claim 7, wherein a fluorinated or fluorinated chlorinated saturated hydrocarbon is used as the organic solvent. 9. The method for producing a fluorine-containing elastomer according to claim 7, which uses tertiary butanol as the organic solvent. 10. The method for producing a fluorine-containing elastomer according to claim 1, 4, or 5, wherein copolymerization is carried out in an aqueous medium using a water-soluble persulfate as a polymerization initiation source.